Improvement in mortising-chisels



G. BUTTLER.

MomrsING-GHISEL; No. 192,148', l Patented .Tune 19, 18774.

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N. PETERS. PHoTd-LITHOGRAPHER. WASHINGTON. D C4 [UNITED STATES PATENT OFFICE GEORGE BU'lTLER, OF NEW BRUN SWIGK, NEW JERSEY.

IMPROVEMENT IN MORTISING-CHISELS.

Specification forming part of LettersPatent No. 192,] 11S, dated June 19, 1877 application tiled June 4, 1877.

. To all whom fit may concern:

Be it known that I, GEORGE BUTTLEE, of New Brunswick, county of Middlesex and State of New Jersey, have invented a new and useful Improvement in Mortising-Ghisels, of which the following is a specification Figure 1 is a front view of my improved chisel. Fig. 2 is a side view of the same, partly in section, through the line w a), Fig. 1. Fig. 3 represents a chip taken out by the chisel. Fig. 4. is a side View, partly in section, showing a modification ot' the chisel. Fig. 5 is a front View, showing another modification of the same. Fig. 6` is a cross-section, taken through the line y y, Fig. 4. Fig. 7 is a crosssection, taken through the line z e, Fig. 5.

Similar letters of reference indicate corresponding parts.

The object of this invention is to furnish an improved chisel, which shall be so constructed as to work easier and do better work than chisels constructed inthe usual way.

The invention consists in a mortising-chisel concaved upon its back and edge, as hereinafter fully described.

In the drawing, A represents the chisel, which is made with a straight front and sides, and with the lowerpart of its back beveled or rounded. The back of the chisel A is concaved longitudinally, which concavity is extended to the edge of the chisel, so as to leave said edge concaved,as shown in Figs. l and 5.

The concavity is also extended laterally to the sides of the, chisel, so as to leave the rear corners or edges of its sides sharp. The concavity in the back of the chisel may be rounded, as shown in Figs. 1 and 6, or angular, as shown in Figs. 5 and 7.

With this coustruction,.when the chisel is v being used, it begins to `cut at the corners of its edge, and the chip has its sides forced hack and up, giving it the appearance of be- `ing a series of ksmall arcs, and making it narrowerthan the chisel, so that it readily passes out of the mortise. This crimping, bending, or contracting of the chip enables the chisel `to be more easily forced into the wood, so that GEORGE BUTTLER.

Witnesses:

JAMES T. GRAHAM, C. SEDGWICK. 

